Meet Llewyn Davis. He’s a loser, a grouch and a misanthrope who uses and abuses his friends while drifting about New York City in 1961 trying to make it as a folk singer.

He’s dejected and half-dead but he’s also one of the most alive and compelling characters to have crossed cinema screens in a while, aided by a riveting, star-making performance by the charismatic Oscar Isaac.

Directed by the Coen brothers, Inside Llewyn Davis is a beautifully realized, bleakly comic portrait of a frustrated artist during a seminal moment in American music: the Greenwich Village folk scene that gave rise to Bob Dylan.

But for a few quirks of fate and his own difficult personality Llewyn Davis, we are encouraged to believe, might have beaten Dylan to it.

Whatever the opposite of reinvention is, Davis is the master of it: he’s a man who simply can’t roll with the times or adapt to new realities. The Times They Are a-Changin’ but Davis won’t change with them.

One half of a double act forced to go solo after the death of his partner, Davis is in a state of existential despair and can’t, or won’t, change his tune (literally) for the success he so desperately needs.

We first meet him in Greenwich Village’s legendary Gaslight Café, hunched over his guitar singing about being hanged. Roll up, roll up!

Whatever the opposite of reinvention is, Davis is the master of it: he’s a man who simply can’t roll with the times or adapt to new realities

He’s heroically, defiantly true to himself, inspiring both admiration and ridicule as he blows around wintry New York with his guitar and a misappropriated cat trying to get his life and career on track.

Imagine a soulful, zipped-up Woody Allen with a guitar and you’ll get the idea. Davis is burningly intense, socially awkward and doomed to failure (narrowly missing out on a big royalty payment, blowing a big audition) but also weirdly lovable and funny.

The joke may be on him but a part of him knows it and even invites it. Monosyllabic on the outside (except when singing) you can imagine a part of him yelling on the inside to the capricious Gods of the universe: “Show me what you got! You ‘aint crushing my soul!”

The result is one of the Coen brothers’ most enjoyable and sincere movies, a low-key but lovingly observed character study infused with a wistful melancholy.

It’s occasionally laugh-out-loud funny but more often dryly amusing as Davis contends with the absurdities of existence and some absurd people.

These include a cutesy folk singer, Jean (Carey Mulligan) whose on-stage persona contrasts with her foul-mouthed fury off it. She’s livid with Davis for getting her pregnant during a recent fling.

Played with fiery glee by Mulligan, she gives Davis an earful whenever she can, which is quite a lot since her small apartment is Davis’ crash pad of choice.

Jean is married to the other half of her stage act, Jim, played by an amusingly twee Justin Timberlake. Davis accuses them of being square careerists who want to live in the suburbs.

Most memorable is the character Davis hopes to meet in Chicago, a club owner and manager with the power to launch Davis’s career.

In a lovely in-joke he’s played by F. Murray Abraham best known for his performance as Mozart’s nemesis Salieri in Amadeus. True to form, this master of the mediocre fails to appreciate Isaac’s talents.

What we’re left with is a resonant portrait of a man blessed with many gifts but unable to capitalize on them. This would appear to be the universe’s - and the Coens - idea of a cruel joke and it’s certainly funny and rather sad, although far from tragic.

Ultimately, Davis is doing what he loves - sing - even if that means living on other people’s couches.

Isaac, a talented musician in his own right, inhabits the role so fully and believably you expect Davis to pop out of the screen cap in hand for a few pennies after a song.

It’s a wonderful performance that, like the picture, lingers in the memory.